The Policy and Charging Control (PCC) architecture and functionality is specified in 3GPP TS 23.203 (v.11.2.0) for Evolved 3GPP Packet Switched domain, including both 3GPP accesses (GERAN/UTRAN/E-UTRAN) and Non-3GPP accesses.
Conventionally, and for the purpose of the present invention, the Policy and Charging Control (PCC) architecture includes a Policy and Charging Enforcement Function (PCEF) in charge of traffic flow detection and enforcement of applicable policies to user traffic flows, a Policy and Charging Rules Function (PCRF) in charge of providing network control for the traffic flow detection by holding policies and providing PCC rules to the PCEF per user traffic flow basis for enforcement of such policies, a Traffic Detection Function (TDF) responsible of performing application detection and reporting detected applications and service data flow descriptions to the Policy and Charging Rules Function (PCRF) for the latter to provide new policies to be enforced by a Policy and Charging Enforcement Function (PCEF), an Application Function (AF) offering applications in which service is delivered in a different layer than the one the service has been requested and in charge of providing to the PCRF information related to session and media negotiated by a user, and a Subscription Profile Repository (SPR) in charge of providing subscription data for a user to the PCRF.
3GPP TS 23.203 (v.11.2.0) describes two ways for the TDF reporting to the PCRF: “Unsolicited”, whereby services to be detected by the TDF are pre-configured in the TDF and are applicable for all users; and “Solicited”, whereby services to be detected are provisioned by the PCRF on a per user and IP Connectivity Access Network (IP-CAN) session basis through provisioning of so-called Application and Detection Control (ADC) rules to the TDF.
Conventionally, the TDF makes use of ADC rules for notifying the PCRF of the beginning and end of application traffic. That is, the ADC rules can be used for identifying Layer 7 applications. In this respect, ADC rules can be used by Deep Packet Inspection (DPI) methods for traffic identification and classification. On the other hand, the PCC rules are significantly simpler than the ADC rules since the PCC rules deal with a Layer 3 Filter or IP 5-tuple. For example, an access to two different applications may be identified just by one single PCC rule, while two ADC rules will be needed for identifying the application properly (for instance, distinguishing between Skype and MSN on top of HTTP traffic).
Moreover, the ADC rules can be applied for all traffic in a whole IP-CAN session, whereas the PCC rules are associated with one bearer each, thus not likely being applicable for the whole IP-CAN session.
3GPP TS 23.203 (v.11.2.0) also defines two different ways for deploying the TDF function: ‘collocated’ with the PCEF, or as a ‘stand-alone’ component. For the TDF-PCEF collocated case, the PCRF may provide at IP-CAN session establishment the ADC rules together with the PCC rules to the TDF-PCEF. But for the stand-alone TDF, a so-called TDF session should be established in order to install the ADC rules.
Even though 3GPP TS 23.203 merely requires the TDF to perform application traffic detection, notification and policy control for the detected application traffic in implementing service awareness policy control, most of the deep packet inspection boxed in the market perform much more IP data traffic treatment, such as content filtering, content insertion, virus detection, data compression, etc.
Since more than one TDF may be required for a same IP-CAN session, each TDF being specialized in different functions, for example, fraud detection, virus scan, data compression, content enrichment, content filtering, etc, there is a need to coordinate each TDF session with the PCEF session, so that each TDF knows when an IP-CAN session, for which the TDF has to perform certain control or reporting, is established, modified or terminated.